A-disubstituted indanone

The enol formed by irradiation of a-disubstituted indanones and tetralones bearing at least one hydrogen in the y-position undergoes enantioselective tautomerization to ketone in the presence of catalytic amounts of optically active aminoalcohols [74]. 

H nin and co-workers reported the results from the irradiation of a-disubstituted indanones, tetralones, and propiophenones bearing at least one hydrogen in the y-position in the presence of catalytic amounts of optically active aminoalcohols. The reaction provided the Norrish type 11 cleavage compounds with an enantiomeric excess reaching 89% (e.g., Scheme 19). Synthesis of 3-hydroxyindene by a Norrish type II elimination as well as the mechanistic aspects of this reaction were discussed by Jefferson and... 

Indanones trani -2,3-Disubstituted indanones are produced in teasonahly good yields from a mixture of atylalkynes and aldehydes with EtOH (1 equiv.) as additive, hy treatment with ShCls. 

The question of the configuration of the enolate and its influence on the stereoselectivity was not addressed. Recently, the protocol was successfully applied to an intramolecular version leading to 2,3-disubstituted indanones in fair diastereoselectivity and enantioselectivity [19a] and to a kinetic resolution of 2-substituted 2,3-dihydroquinolones [19b]. 

The highly electrophilic cationic bis(8-quinolinolato)aluminum complex 407 enabled Yamamoto and coworkers to perform Mukaiyama-Michael additions of silyl enol ethers to crotonylphosphonates 406. The procedure was not only applicable to enol silanes derived from aryl methyl and alkyl methyl ketones (a-unsubstituted silicon enolates) but also to several cycfic a-disubstituted silyl enol ethers, as illustrated for the derivatives of a-methyl tetralone and indanone 405 in Scheme 5.105. Despite the steric demand of that substitution pattern, the reaction occurred in relatively high chemical yield with varying diastereoselectivity and excellent enantiomeric excess of the major diastereomer. The phosphonate residue was replaced in the course of the workup procedure to give the methyl esters 408. The protocol was extended inter alia to the silyl enol ether of 2,6,6-tetramethylcyclohexanone. The relative and absolute configuration of the products 408 was not elucidated [200]. 

Stabilized ketene 6S. For l, 2 -disubstituted epoxide, species 6S undergoes 6-endo-dig electrocyclization (path b) [24] to form the six-membered ketone 66, ultimately giving naphthol products. l, 2, 2 -Trisubstituted epoxide species 6S undergoes 5-endo-dig cyclization (path a) to give the ketone species 67, finally producing l-alkylidene-2-indanones. The dialkyl substituent of the epoxide enhances the 5-endo-dig cyclization of species 65 via formation of a stable tertiary carbocation 67. We observed similar behavior for the cyclization of (o-styryl)ethynylbenzenes [15, 16]. Formation of 2,4-cyclohexadien-l-one is explicable according to 6-endo-dig cyclization of a ruthenium-stabilized ketene, vhich ultimately afforded the observed products [25]. 

Baker s yeast seems to be compatible with several metal-containing or organometal-lic species, as shown for the reduction of ferrocenyl derivatives [459], arylketone-Cr(CO)3 complexes [460], indanone-Cr(CO)3 complexes [460], and a planar chiral metallocene aldehyde [461]. This approach allowed the synthesis of all four enantio-pure stereoisomers of l-ferrocenyl-l,3-butanediol [462] and of 1,1-disubstituted ferrocenyl amino alcohols [463]. The reduction of porphyrins and hemoglobins by baker s yeast is long known there are only a few reports for the reduction of inorganic materials [17]. 

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